The present invention relates to a filter for use in such electronic equipment as used in mobile communication apparatus and the like, particularly intended for dealing with high frequency signals.
LC filters, each formed of inductance elements, capacitor elements and the like that are mounted on a substrate, are disclosed in the Japanese Patent Application Laid Open Publication No. H06-176933, the Japanese Utility Model Application Laid Open Publication No. H04-15812 and the like. The other prior art examples are disclosed in the Japanese Utility Model Application Laid Open Publication No. S61-9918, the Japanese Patent Application Laid Open Publication No. 2000-13167 and the like.
However, according to the structure of filters as disclosed in the aforementioned patents and utility models, no conditions are described with regard to inductance elements that are suitable for use in the filters, particularly when the filters are used in a high frequency region. In addition, such problems as an increasing number of components and a resultant fairly bulky filter configuration have been turning out serious.
A filter of the present invention comprises:
a substrate with a relative dielectric constant of 200 or less and a thickness of 0.1 mm or more;
a first electrode disposed on at least one surface of the substrate;
a group of second electrodes disposed on at least the other surface of the substrate,
each of the group of second electrodes being not in contact with each other and also being not in contact with the first electrode; and
a chip type inductance element, whose terminals are connected with at least two electrodes selected from the group of second electrodes directly or via a conductive adhesive.
The chip type inductance element has an inductance ranging from 0.1 nH to 30 nH and has dimensions of L1 in length, L2 in width and L3 in height, which satisfy the following conditions.
0.3 mm less than L1 less than 2.1 mm 
0.1 mm less than L2 less than 1.1 mm 
0.1 mm less than L3 less than 1.1 mm 
According to the structure disclosed in the present invention, a filter that can realize at least one of such features as having suitable filter characteristics particularly in a high frequency region, realizing a reduction in size and a reduction of a number of components is obtained.